In recent years, contents obtained by compressing digital data of what is called a CD (Compact Disc) on which music information has been recorded by MP3 (MPEG (Moving Picture Experts Group)-1 Audio Layer III) is distributed via the Internet, data read out from the CD is copied onto a CD-R (CD-Recordable) disc, and an exchange service of a music file of a peer-to-peer type which is provided by Napster Co., Ltd. in U.S.A. has been spread, so that a problem of protection of a copyright (hereinbelow, properly referred to as security) has been largely highlighted. Therefore, in novel media which have been proposed in recent years, for example, in recording media such as SACD (Super Audio CD), DVD (Digital Versatile Disc or Digital Video Disc) audio, memory card, etc., the security is held by encrypting the contents. For example, the memory card uses a flash memory and is detachable from an apparatus. When encrypted music data is recorded and stored into the memory card, the apparatus is authenticated and only when the authentication is satisfied, that is, when the apparatus is correctly authenticated, the encrypted data can be stored and recorded into the memory card.
A small optical disc (diameter is equal to 32 mm) proposed by DataPlay Co., Ltd. in U.S.A. uses a copyright protecting technique. Such a technique is constructed by encryption and a technique for controlling reproducing conditions of contents. An “encryption key” to decrypt the encryption performed to the contents and a “condition access key” which specifies access conditions by the user are stored in a dedicated area of a disc inner rim portion which can be accessed only by a copyright protection system.
There is a method whereby information that is indispensable to form key information is recorded into a read only memory area (ROM portion) instead of the key information itself to decrypt the encryption performed to contents data. For example, as an illegal copy preventing technique of a DVD, there has been proposed a technique such that media ID data is recorded in the read only memory area (ROM portion) of an innermost rim portion of a rewritable DVD and contents encrypted by using a hash value of the media ID data and an MKB (Media Key Block) as key data is recorded onto the disc. The media ID data is a value which differs every disc and cannot be rewritten by the user. Thus, even if a data portion is illegally copied onto another disc, since the media ID data differs from media ID data of the disc serving as a copy source, the data portion which was illegally copied cannot be decrypted.
To use the novel media to which the countermeasure for the copyright protection has been made as mentioned above, it is necessary to purchase a new recorder/player. Since it newly causes an economical burden on the user, it becomes an obstacle to widespread the novel media. Even if it is intended to take the countermeasure for the copyright protection to the existing recorders/players, a problem of compatibility is caused or there is a problem such that if it is intended to decrypt the encryption by software installed in a personal computer in order to realize the compatibility, the copyright cannot be sufficiently protected.
It is, therefore, an object of the invention to provide data recording apparatus and method and data reproducing apparatus and method, in which a full-scale security function for encrypting by using a key bound to a media can be easily introduced.